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	$162.58	7.732%	$175.1507	$175.15	$175.15	$175.20
Purchase #2	$70.73	7.785%	$76.2363	$76.24	$76.25	$76.20
Purchase #3	$189.50	3.723%	$196.5551	$196.56	$196.55	$196.60
Purchase #4	$137.31	3.458%	$142.0582	$142.06	$142.05	$142.10
Purchase #5	$24.72	3.246%	$25.5224	$25.52	$25.50	$25.50
Purchase #6	$66.32	8.376%	$71.875	$71.88	$71.90	$71.90
Purchase #7	$150.38	7.329%	$161.4014	$161.40	$161.40	$161.40
7 purchase totals =	$801.54		$848.7991	$848.81	$848.80	$848.90