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	$181.45	7.626%	$195.2874	$195.29	$195.30	$195.30
Purchase #2	$67.37	7.202%	$72.222	$72.22	$72.20	$72.20
Purchase #3	$115.39	7.777%	$124.3639	$124.36	$124.35	$124.40
Purchase #4	$85.91	5.466%	$90.6058	$90.61	$90.60	$90.60
Purchase #5	$57.31	9.238%	$62.6043	$62.60	$62.60	$62.60
Purchase #6	$123.32	4.817%	$129.2603	$129.26	$129.25	$129.30
Purchase #7	$110.73	12.266%	$124.3121	$124.31	$124.30	$124.30
7 purchase totals =	$741.48		$798.6558	$798.65	$798.60	$798.70