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	$184.59	5.521%	$194.7812	$194.78	$194.80	$194.80
Purchase #2	$154.44	6.550%	$164.5558	$164.56	$164.55	$164.60
Purchase #3	$95.85	3.848%	$99.5383	$99.54	$99.55	$99.50
Purchase #4	$48.89	11.764%	$54.6414	$54.64	$54.65	$54.60
Purchase #5	$22.36	12.795%	$25.221	$25.22	$25.20	$25.20
Purchase #6	$236.90	11.462%	$264.0535	$264.05	$264.05	$264.10
Purchase #7	$233.37	5.403%	$245.979	$245.98	$246.00	$246.00
7 purchase totals =	$976.40		$1,048.7702	$1,048.77	$1,048.80	$1,048.80