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	$223.96	5.496%	$236.2688	$236.27	$236.25	$236.30
Purchase #2	$107.71	5.182%	$113.2915	$113.29	$113.30	$113.30
Purchase #3	$106.31	5.279%	$111.9221	$111.92	$111.90	$111.90
Purchase #4	$235.50	8.576%	$255.6965	$255.70	$255.70	$255.70
Purchase #5	$89.74	7.485%	$96.457	$96.46	$96.45	$96.50
Purchase #6	$86.49	6.148%	$91.8074	$91.81	$91.80	$91.80
Purchase #7	$98.25	5.346%	$103.5024	$103.50	$103.50	$103.50
7 purchase totals =	$947.96		$1,008.9457	$1,008.95	$1,008.90	$1,009.00