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	$183.63	3.837%	$190.6759	$190.68	$190.70	$190.70
Purchase #2	$125.40	4.296%	$130.7872	$130.79	$130.80	$130.80
Purchase #3	$133.71	6.558%	$142.4787	$142.48	$142.50	$142.50
Purchase #4	$193.44	12.775%	$218.152	$218.15	$218.15	$218.20
Purchase #5	$61.59	4.543%	$64.388	$64.39	$64.40	$64.40
Purchase #6	$156.31	3.784%	$162.2248	$162.22	$162.20	$162.20
Purchase #7	$141.78	7.426%	$152.3086	$152.31	$152.30	$152.30
7 purchase totals =	$995.86		$1,061.0152	$1,061.02	$1,061.05	$1,061.10