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	$95.35	8.871%	$103.8085	$103.81	$103.80	$103.80
Purchase #2	$21.59	12.263%	$24.2376	$24.24	$24.25	$24.20
Purchase #3	$11.94	7.740%	$12.8642	$12.86	$12.85	$12.90
Purchase #4	$58.77	4.354%	$61.3288	$61.33	$61.35	$61.30
Purchase #5	$100.82	8.524%	$109.4139	$109.41	$109.40	$109.40
Purchase #6	$142.67	3.781%	$148.0644	$148.06	$148.05	$148.10
Purchase #7	$21.73	4.543%	$22.7172	$22.72	$22.70	$22.70
7 purchase totals =	$452.87		$482.4346	$482.43	$482.40	$482.40