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	$233.58	5.280%	$245.913	$245.91	$245.90	$245.90
Purchase #2	$94.62	6.632%	$100.8952	$100.90	$100.90	$100.90
Purchase #3	$185.46	9.118%	$202.3702	$202.37	$202.35	$202.40
Purchase #4	$65.45	11.261%	$72.8203	$72.82	$72.80	$72.80
Purchase #5	$150.86	5.185%	$158.6821	$158.68	$158.70	$158.70
Purchase #6	$238.72	10.689%	$264.2368	$264.24	$264.25	$264.20
Purchase #7	$99.60	6.676%	$106.2493	$106.25	$106.25	$106.20
7 purchase totals =	$1,068.29		$1,151.1669	$1,151.17	$1,151.15	$1,151.10