Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$141.45	7.496%	$152.0531	$152.05	$152.05	$152.10
Purchase #2	$130.34	5.151%	$137.0538	$137.05	$137.05	$137.10
Purchase #3	$105.25	3.430%	$108.8601	$108.86	$108.85	$108.90
Purchase #4	$141.57	3.614%	$146.6863	$146.69	$146.70	$146.70
Purchase #5	$166.89	13.124%	$188.7926	$188.79	$188.80	$188.80
Purchase #6	$200.63	4.851%	$210.3626	$210.36	$210.35	$210.40
Purchase #7	$192.43	3.477%	$199.1208	$199.12	$199.10	$199.10
7 purchase totals =	$1,078.56		$1,142.9293	$1,142.92	$1,142.90	$1,143.10