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	$203.65	4.124%	$212.0485	$212.05	$212.05	$212.00
Purchase #2	$167.85	6.282%	$178.3943	$178.39	$178.40	$178.40
Purchase #3	$140.78	10.203%	$155.1438	$155.14	$155.15	$155.10
Purchase #4	$66.89	6.294%	$71.1001	$71.10	$71.10	$71.10
Purchase #5	$28.33	4.470%	$29.5964	$29.60	$29.60	$29.60
Purchase #6	$36.32	6.424%	$38.6532	$38.65	$38.65	$38.70
Purchase #7	$121.33	5.328%	$127.7945	$127.79	$127.80	$127.80
7 purchase totals =	$765.15		$812.7308	$812.72	$812.75	$812.70