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	$201.36	10.800%	$223.1069	$223.11	$223.10	$223.10
Purchase #2	$62.67	8.323%	$67.886	$67.89	$67.90	$67.90
Purchase #3	$90.36	6.355%	$96.1024	$96.10	$96.10	$96.10
Purchase #4	$43.66	7.793%	$47.0624	$47.06	$47.05	$47.10
Purchase #5	$200.28	9.483%	$219.2726	$219.27	$219.25	$219.30
Purchase #6	$135.83	11.868%	$151.9503	$151.95	$151.95	$152.00
Purchase #7	$48.89	10.356%	$53.953	$53.95	$53.95	$54.00
7 purchase totals =	$783.05		$859.3336	$859.33	$859.30	$859.50