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	$58.33	3.487%	$60.364	$60.36	$60.35	$60.40
Purchase #2	$133.56	6.478%	$142.212	$142.21	$142.20	$142.20
Purchase #3	$250.44	10.259%	$276.1326	$276.13	$276.15	$276.10
Purchase #4	$61.57	10.253%	$67.8828	$67.88	$67.90	$67.90
Purchase #5	$118.27	10.377%	$130.5429	$130.54	$130.55	$130.50
Purchase #6	$158.38	13.410%	$179.6188	$179.62	$179.60	$179.60
Purchase #7	$210.48	4.326%	$219.5854	$219.59	$219.60	$219.60
7 purchase totals =	$991.03		$1,076.3385	$1,076.33	$1,076.35	$1,076.30