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	$82.76	3.841%	$85.9388	$85.94	$85.95	$85.90
Purchase #2	$67.40	11.600%	$75.2184	$75.22	$75.20	$75.20
Purchase #3	$70.68	8.202%	$76.4772	$76.48	$76.50	$76.50
Purchase #4	$77.32	12.362%	$86.8783	$86.88	$86.90	$86.90
Purchase #5	$191.90	13.753%	$218.292	$218.29	$218.30	$218.30
Purchase #6	$179.28	3.374%	$185.3289	$185.33	$185.35	$185.30
Purchase #7	$34.64	11.399%	$38.5886	$38.59	$38.60	$38.60
7 purchase totals =	$703.98		$766.7222	$766.73	$766.80	$766.70