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	$85.25	11.510%	$95.0623	$95.06	$95.05	$95.10
Purchase #2	$126.26	6.611%	$134.607	$134.61	$134.60	$134.60
Purchase #3	$90.96	6.377%	$96.7605	$96.76	$96.75	$96.80
Purchase #4	$89.33	7.110%	$95.6814	$95.68	$95.70	$95.70
Purchase #5	$55.59	3.776%	$57.6891	$57.69	$57.70	$57.70
Purchase #6	$137.69	6.865%	$147.1424	$147.14	$147.15	$147.10
Purchase #7	$98.43	7.398%	$105.7119	$105.71	$105.70	$105.70
7 purchase totals =	$683.51		$732.6546	$732.65	$732.65	$732.70