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	$140.71	3.584%	$145.753	$145.75	$145.75	$145.80
Purchase #2	$142.30	6.799%	$151.975	$151.98	$152.00	$152.00
Purchase #3	$218.35	9.377%	$238.8247	$238.82	$238.80	$238.80
Purchase #4	$232.42	9.327%	$254.0978	$254.10	$254.10	$254.10
Purchase #5	$191.96	4.147%	$199.9206	$199.92	$199.90	$199.90
Purchase #6	$82.45	3.629%	$85.4421	$85.44	$85.45	$85.40
Purchase #7	$66.59	7.360%	$71.491	$71.49	$71.50	$71.50
7 purchase totals =	$1,074.78		$1,147.5042	$1,147.50	$1,147.50	$1,147.50