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	$59.33	5.454%	$62.5659	$62.57	$62.55	$62.60
Purchase #2	$176.67	7.762%	$190.3831	$190.38	$190.40	$190.40
Purchase #3	$79.87	5.578%	$84.3251	$84.33	$84.35	$84.30
Purchase #4	$185.54	3.314%	$191.6888	$191.69	$191.70	$191.70
Purchase #5	$166.66	3.739%	$172.8914	$172.89	$172.90	$172.90
Purchase #6	$49.33	9.834%	$54.1811	$54.18	$54.20	$54.20
Purchase #7	$224.90	8.567%	$244.1672	$244.17	$244.15	$244.20
7 purchase totals =	$942.30		$1,000.2026	$1,000.21	$1,000.25	$1,000.30